Afghanistan's top rights body released its findings into the disputed casualty toll from US air strikes this month, saying up to 97 civilians, most of them children, may have been killed.

Afghanistan's top rights body released on Tuesday its findings into the disputed casualty toll from US air strikes this month, saying up to 97 civilians, most of them children, may have been killed.

An Afghan government investigation found that 140 civilians were killed in the May 4-5 strikes against insurgents in southwestern Farah province, making it one of the deadliest such incidents since the US-led invasion in 2001.

But a US military investigation rejected the toll, saying 20-30 civilians may have been killed as well as 60-65 Taliban.

Afghanistan's Independent Human Rights Commission (AIHRC) questioned the government investigation into the incident in Bala Buluk district, saying it appeared to have been conducted in haste.

The US military had not yet made public a detailed report into its finding, the commission said in a statement.

The commission said it had sent three investigators to the district a few days after the fighting and they had interviewed witnesses, community elders and aid workers.

"AIHRC believes that as many as 97 persons may have been killed in the air strikes, the vast majority civilians," the statement said.

"Available records suggest that 21 were women and 65 were children, 31 of whom were girls and 34 boys," it said.